Foundation and underfloor vents may use mesh size. They are not required to be an ember-intrusion test.

not-an-ember-rated-vent

R327.3.2 allows underfloor ventilation openings to be covered with noncombustible corrosion-resistant metal wire mesh between 1/16 inch and 1/8 inch, or with vents designed to resist burning embers and flame, or other approved materials. Mesh is a sized screen, not ASTM E2886. Presenters at the 25 June 2026 Central Oregon seminar stated foundation vents need screen size, not an ember-intrusion test. Eave underside openings are a different sentence.

As of 2026-06-25. JSON (CC BY 4.0)

Sources

2023 ORSC Section R327 amendment — Oregon Building Codes Division (official). Accessed 2026-08-23.
R327.3.2 mesh minimum 1/16 inch and maximum 1/8 inch, or ember- and flame-resistant vents.
Central Oregon Fire Hardening Codes Seminar — City of Bend Building Safety and Deschutes County Community Development (ahj-interpretation). Accessed 2026-08-23.
Public seminar at Riverhouse Convention Center, Bend, 25 June 2026. FireApproved cites the event and does not host the slide deck.

Foundation and underfloor vents may use mesh size. They are not required to be an ember-intrusion test.. FireApproved. https://fireapproved.com/findings/foundation-vents-mesh-not-ember-test/. As of 2026-06-25.